The invention pertains to a windshield wiper blade assembly.
It is known that at higher vehicular driving speeds many windshield wipers have a tendency to lift from the window pane being cleaned. The resulting impaired wiping affects traffic safety. Many proposals have already been made to solve this problem. In some arrangements a spoiler having a relatively large surface is fixed onto the wiper arm. However, the overall height of the windshield wiper is thereby enlarged, so that this kind of a construction can not be used when the windshield wiper is to be deposited in a so-called submerged parking position between the windshield and the engine hood. In conventional wiper systems visibility through the windshield is affected by a spoiler with a large surface.
The same disadvantages also appear with a windshield wiper having a wiper blade according to the German Patent No. 1,430,623, the main yoke of which is formed as a spoiler pointing away from the wiper element.
U.S. Pat. No. 3,317,946 shows a wiper blade the main-yoke of which has a roof-shaped cross-section. Although its overall height is not necessarily enlarged this construction does not include a central guidance of the supporting yoke system via the connecting element on a wiper arm. "A central guidance of a supporting yoke system" as used herein means a construction in which the connecting element has large areas guided between two parallel guide surfaces of the main yoke. In the embodiment according to U.S. Pat. No. 3,317,946 the connecting element encompasses guide surfaces at the outside of the supporting yoke. In this example the overall height of the wiper blade is thus increased by the design of the wiper arm-and-blade connection.
German specification OS No. 2,346,100 shows a wiper blade in which a spoiler is attached on each of the clawed yokes of the supporting yoke system. The overall height of a wiper blade of this kind corresponds to conventional wipers. However positioning of the spoilers on the clawed yokes does not optimally cure the tendency of the wiper blade to lift from the window pane because the contact pressure is not increased in the central area of the wiper element. Moreover in a construction of this kind the spoilers will touch the window pane, if the window is considerably curved and the wiper element bends correspondingly.
In the wiper blade of German specification OS No. 3,139,444 the main yoke has a substantially U-shaped cross-section with a web for the connection of two side walls projecting therefrom approximately perpendicularly. The side walls form parallel guide surfaces for a connecting element to a wiper arm guided between them. Thus this wiper blade has predominantly central guidance for the wiper arm. A spoiler is held on one side wall of the main yoke via narrow webs. The spoiler screens the central area of the wiper element. Thus the spoiler is not directly adjacent to the side wall of the supporting yoke and therefor has a relatively small effective surface. There is also a risk of the spoiler touching the window pane when the wiper blade is used for cleaning considerably curved lateral window panes.